Atomistic calculations using the Stillinger-Weber and Tersoff interato
mic potentials are used to study the energetics of Si-Ge interchange a
t Si step edges on (001) Ge surfaces. The calculations indicate that G
e segregation at S(B) rebonded step edges is energetically favored. Th
is is consistent with the Ge-pump model of Jesson, Pennycook, and Bari
beau [Phys. Rev. Lett. 66, 750 (199 1)].